2.1 Specifying languages🔗ℹ

This section describes the syntax of the syntax-spec metalanguage, used to describe the grammar, binding structure, and host interface of a DSL.

Language specifications are made via the subforms of syntax-spec, which must be used at module-level.

syntax (syntax-spec spec-def ...)

spec-def   =   binding-class     |   extension-class     |   nonterminal     |   host-interface

The following subsections address each kind of declaration allowed within the syntax-spec form.

2.1.1 Binding classes🔗ℹ

Binding classes distinguish types of binding. When a reference resolves to a binder, it is an error if the binding class declared for the reference position does not match the binding class of the binding position.

syntax (binding-class id maybe-description maybe-binding-space)

maybe-description   =   #:description string-literal     |             maybe-binding-space   =   #:binding-space space-symbol     |

The #:description option provides a user-friendly phrase describing the kind of binding. This description is used in error messages.

The #:binding-space option specifies a binding space to use for all bindings and references declared with this class.

Operationally, the binding space declaration causes the syntax-spec expander to add the binding space scope to bindings and references. The scope is added to the scope sets of all binding occurrences. When parsing a reference position declared with a binding class that has an associated binding space, the name that is looked up is augmented with the binding class scope in order to give it access to bindings defined in the space.

2.1.2 Extension classes🔗ℹ

syntax (extension-class id maybe-description maybe-binding-space)

maybe-description   =   #:description string-literal     |             maybe-binding-space   =   #:binding-space space-symbol     |

2.1.3 Nonterminals🔗ℹ

2.1.3.1 Nonterminal options🔗ℹ

2.1.3.2 Productions🔗ℹ

2.1.4 Syntax specs🔗ℹ

2.1.5 Binding specs🔗ℹ

2.1.6 Defining host interface forms🔗ℹ

syntax (host-interface/expression   (id . syntax-spec)   maybe-binding-spec   pattern-directive ...   body ...+)

syntax (host-interface/definition   (id . syntax-spec)   maybe-binding-spec   #:lhs   [pattern-directive ...    body ...+]   #:rhs   [pattern-directive ...    body ...+])

syntax (host-interface/definitions   (id . syntax-spec)   maybe-binding-spec   pattern-directive ...   body ...+)

2.1.7 Embedding Racket syntax🔗ℹ

nonterminal racket-expr

binding class racket-var

extension class racket-macro